1. Field of the Invention
The present invention relates to an organic light emitting device (OLED), and more particularly, to a white OLED.
2. Description of the Related Art
Organic light emitting devices (OLEDs) emit light by combining electrons and holes in an organic light emitting layer when current or voltage is applied to the organic light emitting layer. OLEDs may have a multi-layer structure including a hole injection layer (HIL) and a hole transporting layer (HTL) disposed between an anode and an organic light emitting layer, and an electron injection layer (EIL) and an electron transporting layer (ETL) disposed between a cathode and the organic light emitting layer to obtain higher luminous efficiency.
OLEDs have the advantages of a low driving voltage of approximately 5 V, high brightness, a short response time, thin design, good color reproduction, a wide viewing angle, and easy change of color through a selection of a fluorescent material. Accordingly, OLEDs can be used in various applications including a full color display device, a backlight unit for a liquid crystal display (LCD), an information display device, an automotive display device, and an illumination device.
White OLEDs, which emit white light, have a structure in which light emitting layers emitting light of various colors are stacked. In particular, white OLEDs can be used as a paper-thin light source, a backlight unit for an LCD, and a full color display device employing a color filter. However, white OLEDs have a disadvantage in that it is difficult to control chromaticity because the light emitting layers simultaneously emit light of various colors. In detail, since the light emitting layers are different from one another in terms of the quantity of charges injected thereinto, charge mobility therein, and energy level, it is difficult to control chromaticity.